<div dir="ltr">Also note that it is not currently feasible for UDL code to access drm_global_mutex.<div> </div><div>Please also refer to the similar comments ("FIXME: open_count is protected by drm_global_mutex but that would lead to locking inversion with the driver load path.") in nouveau, i915 and amdgpu.</div></div><div class="gmail_extra"> <div class="gmail_quote">On Wed, Feb 10, 2016 at 12:51 PM, Haixia Shi <<a href="mailto:hshi@chromium.org" target="_blank">hshi@chromium.org</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">> This should rather be: > > drm_release(inode, filp); > mutex_lock(&drm_global_mutex); > if (!dev->open_count && udl_device_is_unplugged(dev)) > drm_put_dev(dev); > mutex_unlock(&drm_global_mutex); > > return 0; > > There is no reason to look at the return code of drm_release(), ever. <div> </div><div>But drm_release() does return a retcode. It would still make sense to return that as-is in case any existing code relies on it.</div></div><div class="gmail_extra"> <div class="gmail_quote">On Wed, Feb 10, 2016 at 4:24 AM, David Herrmann <<a href="mailto:dh.herrmann@gmail.com" target="_blank">dh.herrmann@gmail.com</a>> wrote: <div><div class="h5"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi <div><div> On Tue, Feb 9, 2016 at 10:05 PM, Haixia Shi <<a href="mailto:hshi@chromium.org" target="_blank">hshi@chromium.org</a>> wrote: > Remove the general drm_device_is_unplugged() checks, and move the unplugged > flag handling logic into drm/udl. In general we want to keep driver-specific > logic out of common drm code. > > Signed-off-by: Haixia Shi <<a href="mailto:hshi@chromium.org" target="_blank">hshi@chromium.org</a>> > Reviewed-by: Stéphane Marchesin <<a href="mailto:marcheu@chromium.org" target="_blank">marcheu@chromium.org</a>> > --- > drivers/gpu/drm/drm_drv.c | 6 ---- > drivers/gpu/drm/drm_fops.c | 2 -- > drivers/gpu/drm/drm_gem.c | 3 -- > drivers/gpu/drm/drm_ioctl.c | 3 -- > drivers/gpu/drm/drm_vm.c | 3 -- > drivers/gpu/drm/udl/udl_connector.c | 2 +- > drivers/gpu/drm/udl/udl_drv.c | 7 +++-- > drivers/gpu/drm/udl/udl_drv.h | 6 ++++ > drivers/gpu/drm/udl/udl_fb.c | 2 +- > drivers/gpu/drm/udl/udl_gem.c | 5 +++ > drivers/gpu/drm/udl/udl_main.c | 61 +++++++++++++++++++++++++++++++++++++ > include/drm/drmP.h | 14 --------- > 12 files changed, 78 insertions(+), 36 deletions(-) > > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c > index 167c8d3..f93ee12 100644 > --- a/drivers/gpu/drm/drm_drv.c > +++ b/drivers/gpu/drm/drm_drv.c > @@ -376,9 +376,6 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id) > > if (!minor) { > return ERR_PTR(-ENODEV); > - } else if (drm_device_is_unplugged(minor->dev)) { > - drm_dev_unref(minor->dev); > - return ERR_PTR(-ENODEV); > } > > return minor; > @@ -464,9 +461,6 @@ void drm_unplug_dev(struct drm_device *dev) > drm_minor_unregister(dev, DRM_MINOR_CONTROL); > > mutex_lock(&drm_global_mutex); > - > - drm_device_set_unplugged(dev); > - > if (dev->open_count == 0) { > drm_put_dev(dev); > } > diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c > index 1ea8790..b4332d4 100644 > --- a/drivers/gpu/drm/drm_fops.c > +++ b/drivers/gpu/drm/drm_fops.c > @@ -497,8 +497,6 @@ int drm_release(struct inode *inode, struct file *filp) > > if (!--dev->open_count) { > retcode = drm_lastclose(dev); > - if (drm_device_is_unplugged(dev)) > - drm_put_dev(dev); > } > mutex_unlock(&drm_global_mutex); > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index 2e8c77e..c622e32 100644 > --- a/drivers/gpu/drm/drm_gem.c > +++ b/drivers/gpu/drm/drm_gem.c > @@ -900,9 +900,6 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma) > struct drm_vma_offset_node *node; > int ret; > > - if (drm_device_is_unplugged(dev)) > - return -ENODEV; > - > drm_vma_offset_lock_lookup(dev->vma_offset_manager); > node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager, > vma->vm_pgoff, > diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c > index 8ce2a0c..f959074 100644 > --- a/drivers/gpu/drm/drm_ioctl.c > +++ b/drivers/gpu/drm/drm_ioctl.c > @@ -695,9 +695,6 @@ long drm_ioctl(struct file *filp, > > dev = file_priv->minor->dev; > > - if (drm_device_is_unplugged(dev)) > - return -ENODEV; > - > is_driver_ioctl = nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END; > > if (is_driver_ioctl) { > diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c > index f90bd5f..3a68be4 100644 > --- a/drivers/gpu/drm/drm_vm.c > +++ b/drivers/gpu/drm/drm_vm.c > @@ -657,9 +657,6 @@ int drm_legacy_mmap(struct file *filp, struct vm_area_struct *vma) > struct drm_device *dev = priv->minor->dev; > int ret; > > - if (drm_device_is_unplugged(dev)) > - return -ENODEV; > - > mutex_lock(&dev->struct_mutex); > ret = drm_mmap_locked(filp, vma); > mutex_unlock(&dev->struct_mutex); > diff --git a/drivers/gpu/drm/udl/udl_connector.c b/drivers/gpu/drm/udl/udl_connector.c > index 4709b54..b168f2c 100644 > --- a/drivers/gpu/drm/udl/udl_connector.c > +++ b/drivers/gpu/drm/udl/udl_connector.c > @@ -96,7 +96,7 @@ static int udl_mode_valid(struct drm_connector *connector, > static enum drm_connector_status > udl_detect(struct drm_connector *connector, bool force) > { > - if (drm_device_is_unplugged(connector->dev)) > + if (udl_device_is_unplugged(connector->dev)) > return connector_status_disconnected; > return connector_status_connected; > } > diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c > index d5728ec..f5c2a97 100644 > --- a/drivers/gpu/drm/udl/udl_drv.c > +++ b/drivers/gpu/drm/udl/udl_drv.c > @@ -24,12 +24,12 @@ static const struct vm_operations_struct udl_gem_vm_ops = { > > static const struct file_operations udl_driver_fops = { > .owner = THIS_MODULE, > - .open = drm_open, > + .open = udl_drm_open, > .mmap = udl_drm_gem_mmap, > .poll = drm_poll, > .read = drm_read, > - .unlocked_ioctl = drm_ioctl, > - .release = drm_release, > + .unlocked_ioctl = udl_drm_ioctl, > + .release = udl_drm_release, > #ifdef CONFIG_COMPAT > .compat_ioctl = drm_compat_ioctl, > #endif > @@ -97,6 +97,7 @@ static void udl_usb_disconnect(struct usb_interface *interface) > drm_connector_unplug_all(dev); > udl_fbdev_unplug(dev); > udl_drop_usb(dev); > + udl_device_set_unplugged(dev); > drm_unplug_dev(dev); > } > > diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h > index 4a064ef..75aa91c 100644 > --- a/drivers/gpu/drm/udl/udl_drv.h > +++ b/drivers/gpu/drm/udl/udl_drv.h > @@ -65,6 +65,7 @@ struct udl_device { > atomic_t bytes_identical; /* saved effort with backbuffer comparison */ > atomic_t bytes_sent; /* to usb, after compression including overhead */ > atomic_t cpu_kcycles_used; /* transpired during pixel processing */ > + atomic_t unplugged; /* device has been unplugged or gone away */ > }; > > struct udl_gem_object { > @@ -133,6 +134,9 @@ int udl_gem_get_pages(struct udl_gem_object *obj); > void udl_gem_put_pages(struct udl_gem_object *obj); > int udl_gem_vmap(struct udl_gem_object *obj); > void udl_gem_vunmap(struct udl_gem_object *obj); > +int udl_drm_open(struct inode *inode, struct file *filp); > +int udl_drm_release(struct inode *inode, struct file *filp); > +int udl_drm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg); > int udl_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma); > int udl_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf); > > @@ -140,6 +144,8 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y, > int width, int height); > > int udl_drop_usb(struct drm_device *dev); > +void udl_device_set_unplugged(struct drm_device *dev); > +int udl_device_is_unplugged(struct drm_device *dev); > > #define CMD_WRITE_RAW8 "\xAF\x60" /**< 8 bit raw write command. */ > #define CMD_WRITE_RL8 "\xAF\x61" /**< 8 bit run length command. */ > diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c > index 200419d..df1d53e 100644 > --- a/drivers/gpu/drm/udl/udl_fb.c > +++ b/drivers/gpu/drm/udl/udl_fb.c > @@ -325,7 +325,7 @@ static int udl_fb_open(struct fb_info *info, int user) > struct udl_device *udl = dev->dev_private; > > /* If the USB device is gone, we don't accept new opens */ > - if (drm_device_is_unplugged(udl->ddev)) > + if (udl_device_is_unplugged(udl->ddev)) > return -ENODEV; > > ufbdev->fb_count++; > diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c > index 2a0a784..33c302f 100644 > --- a/drivers/gpu/drm/udl/udl_gem.c > +++ b/drivers/gpu/drm/udl/udl_gem.c > @@ -86,8 +86,13 @@ int udl_dumb_create(struct drm_file *file, > > int udl_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma) > { > + struct drm_file *priv = filp->private_data; > + struct drm_device *dev = priv->minor->dev; > int ret; > > + if (udl_device_is_unplugged(dev)) > + return -ENODEV; > + > ret = drm_gem_mmap(filp, vma); > if (ret) > return ret; > diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c > index 33dbfb2..2ba3ee3 100644 > --- a/drivers/gpu/drm/udl/udl_main.c > +++ b/drivers/gpu/drm/udl/udl_main.c > @@ -350,3 +350,64 @@ int udl_driver_unload(struct drm_device *dev) > kfree(udl); > return 0; > } > + > +int udl_drm_open(struct inode *inode, struct file *filp) > +{ > + struct drm_file *file_priv; > + struct drm_minor *minor; > + > + int ret = drm_open(inode, filp); > + if (ret) > + return ret; > + > + file_priv = filp->private_data; > + minor = file_priv->minor; > + if (udl_device_is_unplugged(minor->dev)) { > + drm_dev_unref(minor->dev); > + return -ENODEV; > + } </div></div>This doesn't make sense to me. You're called here with global-mutex held, so you can just check udl_device_is_unplugged() before calling into drm_open(). > + > + return 0; > +} > + > +int udl_drm_release(struct inode *inode, struct file *filp) > +{ > + struct drm_file *file_priv = filp->private_data; > + struct drm_device *dev = file_priv->minor->dev; > + > + int ret = drm_release(inode, filp); > + if (!dev->open_count && udl_device_is_unplugged(dev)) > + drm_put_dev(dev); This should rather be: drm_release(inode, filp); mutex_lock(&drm_global_mutex); if (!dev->open_count && udl_device_is_unplugged(dev)) drm_put_dev(dev); mutex_unlock(&drm_global_mutex); return 0; There is no reason to look at the return code of drm_release(), ever. > + > + return ret; > +} > + > +int udl_drm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > +{ > + struct drm_file *file_priv = filp->private_data; > + struct drm_device *dev = file_priv->minor->dev; > + unsigned int nr = DRM_IOCTL_NR(cmd); > + > + if (udl_device_is_unplugged(dev) && > + nr != DRM_IOCTL_NR(DRM_IOCTL_MODE_SETCRTC) && > + nr != DRM_IOCTL_NR(DRM_IOCTL_MODE_RMFB) && > + nr != DRM_IOCTL_NR(DRM_IOCTL_MODE_DESTROY_DUMB)) > + return -ENODEV; Why? Just do: if (udl_device_is_unplugged(dev)) return -ENODEV; Why this complex logic here? Thanks David <div><div> > + > + return drm_ioctl(filp, cmd, arg); > +} > + > +void udl_device_set_unplugged(struct drm_device *dev) > +{ > + struct udl_device *udl = dev->dev_private; > + smp_wmb(); > + atomic_set(&udl->unplugged, 1); > +} > + > +int udl_device_is_unplugged(struct drm_device *dev) > +{ > + struct udl_device *udl = dev->dev_private; > + int ret = atomic_read(&udl->unplugged); > + smp_rmb(); > + return ret; > +} > diff --git a/include/drm/drmP.h b/include/drm/drmP.h > index d7162cf..40c6099 100644 > --- a/include/drm/drmP.h > +++ b/include/drm/drmP.h > @@ -748,7 +748,6 @@ struct drm_device { > struct drm_minor *control; /**< Control node */ > struct drm_minor *primary; /**< Primary node */ > struct drm_minor *render; /**< Render node */ > - atomic_t unplugged; /**< Flag whether dev is dead */ > struct inode *anon_inode; /**< inode for private address-space */ > char *unique; /**< unique name of the device */ > /*@} */ > @@ -879,19 +878,6 @@ static __inline__ int drm_core_check_feature(struct drm_device *dev, > return ((dev->driver->driver_features & feature) ? 1 : 0); > } > > -static inline void drm_device_set_unplugged(struct drm_device *dev) > -{ > - smp_wmb(); > - atomic_set(&dev->unplugged, 1); > -} > - > -static inline int drm_device_is_unplugged(struct drm_device *dev) > -{ > - int ret = atomic_read(&dev->unplugged); > - smp_rmb(); > - return ret; > -} > - > static inline bool drm_is_render_client(const struct drm_file *file_priv) > { > return file_priv->minor->type == DRM_MINOR_RENDER; > -- > 2.7.0.rc3.207.g0ac5344 > </div></div></blockquote></div></div></div> </div> </blockquote></div> </div>